Aircraft propulsion



S. D. MOTT.

AIRCRAFT PRDPULSION` APPLICATION FILED APR. I, I9Is.

1,361,276. Patented Dee. 7,1920.

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AIRCRAFT PRbPuLSloN.

APPLICATION FILED APH. I. 1916.

Patented Dec. 7, 1920.

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Pfam# WITNESSES Ano/INEI;

` UNITED.. STAT-Es SAMUEL D. MOTT, OF PASSAIC, NEW JERSEY, ASSIGNOR 0F ONE-HALF TO ARTHUR IB.

PATENT OFFICE. N

SULLIVAN, OF ALLENDALE, NEW JERSEY.

-AInoRAFT PRoPULsIoN.

' Application filed April 1,

T o aZZ whomt may concern:

Be it known that I, SAMUEL D. Mo'i'r, a citizen of the United States, resident of and whose post-office address is 130 Autumn street, in the city of Passaic, county of Passaic, and State of New Jersey, have inventedy certain new and` useful Improvements in Aircraft Propulsion, of which the following is a description, reference bein had to the drawings forming a part hereo Among the objects of my inventionare the utilization'of means adapted to make the power absorbed by the propeller on aircraft more effective, to reducethe air resistance of the body of the aircraft, to neutralize or compensate rotary or centrifugal effect, and for various other purposes.

`When a propeller is held in place and rotated rapidly it churns the air, whereas any retardation of movement of the air will cause a tendency to displacement of the propeller resulting from increased resistance. It is expressed frequently that the propeller to get propulsion effect or reaction must act on new medium or undisturbed medium such as air. I have found by experiment that with a strong transverse wind the resistance of the propeller lis greater than ,when the propeller is rotating in inert air, consequently assisting in the effective reaction for propulsion, which is the object of the action of the propeller in aircraft.

I therefore arrange a fan` in proximity to the propeller which will project air radially from the axis of the propeller shaft, and

with ther movement of the aircraft, such air given a radial velocity will bank in the zone of movement of the propelling blades, thereby increasing the reactive character of the medium on which the propeller is acting. It is practically furnishing the propellers constantly more air than they would otherwise engage in the manner in which they are now usually employed.

' By such arrangement, in the case'of an aeroplane with the propellers in the front of the fuselage, the fan serves to radially distribute the air, thereby reducing the Vhead 'resistance and skin friction in the forward partof the machine.

In brief, therefore, one of the mam objects of my invention is to increase the effi' ciency of propellers, While also reducmg'resistance and counter-balancing the reaction of the motive power and also counter-bal- Specication of Letters Patent.

Patented Dec. 7, 1920. 1916. Serial No. 88,192. i

' ofmotors.

Fig. 3 is a front 'elevation of fan and propeller to diagrammatically illustrate their v operation.

The engines and shaft connections and structure of fans and propellers are not intended to be working drawings, but merely serve to illustrate the relative arrangement of parts, the actual construction and arrangement of which would be made for proper assembly and convenience strength of manufacture-by designers, for the particular c'ase that may be involved for embodiment of my invention.

In the particular form herein shown andv described, A is the forward end of a fuselage, B is a motor, D is a propeller, E--E are propeller blades, F is a fan with blades G and hub G', with spokes g, H is a drive shaft for the fan F, J is a drive shaft for the propeller D connected by means of the hub D and spokes el, while spokes d conneet with a hub flange also jattached to the drive shaft J. A

IThilenconcentric shafts heretofore have been shown in patents granted to me and other types of aircraft, it will be noted that the inner shaft Hadrives a fan not intended for propulsion, but for Ith purpose of directing air currents intothe zone of reaction of the propeller D. The operation of these ,concentric shafts involves the bearing in the application Serial No. 88,193 although any suitable form of motor may be used. As illustrated in the particular form shown. lthe motor cylinders b-b are supported rigid ywith relation to the shaft J, while the crank shaft M through bevel gear m drives and and the pinions m on the crank shafts M react' on the stationary bevel gears P-P, held rigid by anysuitable frame work Q, so that the operation of the motor results in a reaction turning the respective shafts to which they are attached. In this arrangement, suitable control mechanism permits the adjustment of speed of each of the engines irrespective of the other, so that the desired speed found most advantageous for the fan F will be established, and the speed desired for the propeller D will be established entirely within thel control of Ythe operator. In the case of` a single engine, as shown in Fig. l, a relation of the size of fan blades and their contour and the size and pitch and other characteristics of the propeller may be so proportioned that the relative resistance of fan and propeller will` cause a balance provoking the desired absolute rotary speed of each.- However, as air pockets and possible variations in internal resistance of the propelling mechanism are likely to interfere with-the desired balance of operation of the two members, it is well to embody suitable brake or dampening device to relatively -retard one or the other of the shafts, which may be done by any desired known means and by the use of a suitable tachometer in the view of the operator, the relative operation of the members can be noted and the control effected accordingly. It maybe noted that in starting a preponderance of propeller speedmay be desired, whereas under certain conditions the reverse may be true, and on this account the absolute control of both shafts may be perfected.

'In Fig. 3 the blades G of the\fan are indicated by arrows showing the direction of rotation, while the blades E-E-E of the propeller have arrows showing their direction of rotation.

The dotted'radial arrows indicate the general directions in which the fan F will project the air it encounters, and in Fig. 1 arrows similarlyY indicate the movement of air, while the diagonal arrows indicate the resultant drift of the air due to the radial propulsion by the fan and the forward movement of the aircraft, so that the current of air caused by the fan will pass through the zone of action of the propeller D, which in turn drives the air rearward, as indicated by the arrows R, thereby clearing the fuselage, in the case of an aeroplane structure, as indicated in the particular form illus-- trated. To an extent the relief of head resistance is accompanied with a tendency to partial vacuum, which further minimizes the head resistance besides reducing skin resistance.

The exact construction of' fan and propeller by means of the hubs and spokes, as,

diagrammatically illustrated, involves the invention more particularly shown and described in other co-pending applications for Letters Patent and need not be more specifically described herein.

By observation and experiment I have ascertained that a strong wind blowing athwart the direction of movement of a flying device, supplies new air and increases the reactive effect of a propeller. lVere it possible to propel air at a great velocity the resistance ofthe air to deflection from its course would be very materially increased, as compared with the reaction of still air, or in other words rapidly moving air would ofler increasingly greater medium of reaction. The effect of radially projecting air by means of the fan in my invention, will toa greater or less degree increase the resistance of the air to offer the react-ion of the propeller in like manner. So many factors enter into the question of propulsion, that the relative speeds, sizes of propellers, the nature or size of the fan, and the power involved are all relatively to be determinable for any specific case, `and it will therefore be seen that various modifications may be made of the exact form herein shown and described, without departing from'the spirit of' my invention. The arrangement of fan to the rear instead of the -front of the plane of the propeller, may be preferable in some cases. The cooperation cfa fan as shown, of a maximum diameter equal to the diameter of the central free space between the propeller blades, vhas certain advantages, but involves a suspended propeller with a substantially free circular zone about its hub, which is possible when utilizing the propeller supporting structure shown in my co-pending application Serial No. 66,466.

-This permits the action ofthe fan in a cylindrical zone with the propeller action in an outer annular cylindrical zone, as shown in Fig; il; whereas in Fig. 3, a modified arrangement is diagrammatically illustrated in which the fan is most naturally in front ofthe propeller blades. It will be noted that the practice of my invention results in giving a radial com onent to the movement 4 of the air mass 1n w ich the propeller operates, and the greater the speed of the air where engaged by the propeller blades, the greater will be the reaction imparted to the blades 'with the resultant advantage. As

the mass of air will move in a direction inluenced by the two components, namelythe relative movement of the machine'and the radial movement due to the fan, means a re,- sultant between the two directions which will give a bank of air at high speed in the zone of the propeller, moving in an advantageous direction for the desired purpose.

While the fan F hasbeen shown as having direct radial blades, the desired speed of the aircraft and-the predetermined rotary speed of the fan will determine the shape and contour of the fan blades, while the structural parts to transmit the desired power'tol the blades will be carried out in a suitable mechanical 4manner varying from the ldiagrammatic illustration herein shown.

It may be desirable in some cases to warp the fan blades and to materially changey their shape, with the object of throwing the desired volume of air radially in the direction most eilicient under the conditions in volved in any particular case. wLikewise, while the propeller blades are simply indicated in a general form, the exact shape and pitch and structure will be determined by the factors involved in any particular case, using the experience and practice now familiar to one skilled in the art and the rapidly developing experience of the day.

The opposite rotation of the dr1vinQ` elements, as well as the fan yand propeller per while serving the .particular purpose above described, will neutralize any tendency to gyroscopic effect which might be involved at high speeds. Should geared down motors be used, thereby running at much greater speed, than the fan and propeller respectively, their tendency to any gyroscopic effect or reaction will be greater and the opposite rotation of the mam elements proportionately of greater benefit.

The banking of air in the zone of reaction of the propeller, or as it may be, the movement of air at great velocity transverse to the reaction of the propeller will have its material effect and be the subject of much thorough.y investigation and determination of characteristics, so that my 1nvention may be readily applied to any specific'case of design involved.

While innumerable modificatlonsmay be made in structure, arrangement or operation, and many details may be added for control, refinementv or rellability and other desired qualities of aircraft propulsion,

Awithout departing from my invention, what 'I claim and desire to secure by Letters Pat ent is 1. -In an aeroplane, thecombination ofa lshaft and having a` zone of action exterior to the fuselage and a fan rotating in a plane forward of the plane of rotation of the propeller and concentrically therewith and having its maximum diameter less than the effective reactive area of the ropeller blades, said fan having blade sur aces adapted to project the air core into which the fuselage is advancing radially outward into a zone in front of the forward surfaces of said propeller blades whereby in its propulsive action the sai propeller will drive the air rearward clear of the fuselage.

2. Means of propulsion for aeroplanes,

comprising a motor shaft, a horizontal shaft projecting from the fuselage and substantially, coinciding with the fuselage axis, a

4propeller rotatedthereby and having its,

effective zone of action exterior to the path of the fuselage as the machine moves f orward, and a concentric shaft having a fan rotated thereby in front of the fuselage and in a plane displaced from the plane of rotation of the propeller, said fan having air surfaces adapted to expend the motor energy primarily in projecting the air radially from the path of the fuselage and outward to the area of yeffective reaction of the propeller.

3. The combination with an aircraft of` propulsion apparatus therefor, comprising two oppositely' movin concentric shafts, a propeller on one of sai shafts having blades reacting in the direction of the axis and having a zone of action such that the air driven rearwardly thereby clears the body of the machine, and fankblades on the other of said shafts rotating in a plane in advance of the plane of action of the propeller, said fan blades being adapted to project the air in the zone embracing the path of the body of the machine radially outward into an exterior zone in front of the propeller as andl for the purpose described.

In testimony whereof yI have signed my name to vthis specification, in the presence of two subscribing witnesses, this 28 day of March, 1916.

SAMUEL D. MOTT. Witnesses: y

HERMANN F. CUN'rz. j H. MUoHMoRE. 

